"Basically, we examined both the number of days warm enough for the pests to grow and the number of days cold enough to kill the pests, assuming the pests' documented climate tolerances remain the same," Krupke said. "This tells us what could happen in projected future climates. However, the model cannot take into account the dynamic nature of any ecological system. There are significant additional factors that could come into play such as interaction of the pests with the environment, relocation of corn and other crops and changing human management of the pests."
The research team studied the potential end-of-the-century distributions of the corn earworm, Heliothis zea; the European corn borer, Ostrinia nubilalis; northern corn rootworm, Diabrotica barberi; and western corn rootworm, Diabrotica virgifera virgifera.
The team used the physiological thresholds for each species coupled with models of development to determine how each would respond to projected climate change scenarios.
For example, the pupal stage of the corn earworm overwinters and cannot withstand more than five days at temperatures below 14 degrees Fahrenheit. It also requires six days at a temperature of about 55 degrees Fahrenheit to complete development. By including these parameters in the climate model, the team was able to project future temperature-based distributions for each pest, Diffenbaugh said.
Krupke said the insects in this study should not be adversely affected by temperature increases.
"The limiting factor for these pests is usually cold tolerance, specifically their ability to overwinter and re-infest the crop the next season," he said. "Increases in temperatures, even summer temperatures, gene
|Contact: Elizabeth K. Gardner|